Embodiments of the present invention relate to a computed tomography method, a computer program, a computing device and computed tomography system for determining a volumetric representation of a sample.
It is a general demand in computed tomography to reduce the influence of artefacts, to reduce the reconstruction time and to improve the quality of the reconstructed volume data.
Beyond this general demand, in many cases there exists the problem that certain regions of a given object cannot be scanned completely, or penetrated sufficiently, by x-rays during data acquisition, leading to regions of poor quality in the reconstructed volume data. Such cases relate for example to large objects which cannot be completely scanned in particular over the full 360°, like large flat components such as electronic boards; and/or materials which are hard to penetrate with x-rays, like lead in solder joints or inconel in turbine blades.
U.S. Pat. No. 6,862,335 B2 discloses a computed tomography method comprising an analytic reconstruction step for generating an initial reconstruction volume data, a volume partitioning step for separating the initial reconstruction volume into a good volume having a relatively good image quality and a poor volume having a relatively poor image quality, and an iterative reconstruction step for refining the reconstruction volume data in the poor volume. The volume partitioning step is based on geometrical considerations, namely the poor volume is defined by regions which are traversed by a relatively small number of radiation paths whereas the good volume is defined by regions which are traversed by a relatively large number of radiation paths, leading to a fixed and gross separation into good and poor volume parts for a given CT scanner geometry.